To improve stability and antimicrobial activity of negamycin (NGM) in ointment preparation, chemical stability and in vitro release of NGM incorporated in ointment cking water phase and the combination effect of NGM and other antibiotics were investigated. In vitro release of NGM from fatty alcohol and propylene glycol base was greater than that from plastibase 50W and hydrophilic poloid. The release rate of NGM was further improved by modifying ingredients and compositions of FAPG base. The combinations of NGM and other antibiotics significantly improved antimicrobial activity against gram-positive bacterium, particularly the combination of NGM and tetracycline. The present data suggest the utility of FAPG base and the efficacy of the combination of NGM and tetracycline in the preparation of NGM ointment.
